Hydrocarbon peroxides



5...... Aug. 24, 194s HYDBOCARBON PEBOXIDES Philip D. Brewer, LongBeach, Calif" Union Oil Company of California,

Los CaliL, a corporation of California liner to No drawing. ApplicationJanuary 30, 1045, Serial No. 575.356

8 Claims. ((21.280-410) This invention relates to hydrocarbon peroxidesand particularly to improvements in the method of production ofhydrocarbon peroxides by the liquid phase oxidation of hydrocarbons orhydrocarbon fractions and is a contihuation-inpart of my copendingapplication Serial No. 522,- 839 filed February 1'1, 1944.

In many oxidation processes and particularly a in liquid phase, air oroxygen-containing gas oxidation processes for the production of partialm oxidation products from hydrocarbon feeds the presence of peroxides inthe oxidate has been observed. However, in general the peroxide contentof the oxidate reaches a maximum of between about 0.5% to about 5.0% byweight of the charge, depending upon the conditions of oxidation andupon the stock and then decreases rapidly as the oxidation proceeds. Inthose cases in which peroxides are the desired oxidation products theoxidation is discontinued when the peroxide content has reached amaximum and the peroxides are then separated from the oxidate by variousphysical or chemical means to produce a useable peroxide concentrate.

It is an object of my invention to provide a method for the controlledliquid phase oxidation of hydrocarbons to produce a substantialproportion of hydrocarbon peroxides.

It is another object o! my invention to provide a method for theproduction of hydrocarbon peroxides involving contacting saidhydrocarbon with a gas containing free oxygen in thepresence of abasically reacting agent, which agent form's salts with acids producedduring the oxidation.

It is a further object of my invention to provide a new and improvedmethod for the production of hydrocarbon peroxides by a processinvolving contacting said hydrocarbon with an oxygen-containing gas inthe presence of a metal of the alkaline earth group, or a basic compound40 of one of these metals, whereby the proportion of peroxides in theoxidate is-substantially increased over that proportion obtained withoutthe use of said metal or basic metal compound.

2 vide a method for the production of a hydrocarbon oxidate containingsubstantial proportions of hydrocarbon peroxides which has value,without the iurther concentration of said peroxides,

as an improver for Diesel .fuel in order to increase cetane valuethereof.

The invention resides in oxidizing a hydrocarbon or a hydrocarbonfraction in the liquid phase in the presence of an amount of a basicallyreacting agent aufflcient to react with substantially allof the formsalts.

presence of ide content acids formed during the oxidation to Y rryi gout my oxidation in the a basically reacting agent the peroxof theresulting oxidate may be substantially greater than that obtainable by,oxidizing in the absence of such agents.

1 have iound, for example, that by air blowing an Edeleanu treatedkerosene at ordinary atmospheric pressures and at a temperature of about250 F, in the presence of about 3.0% by weight or powdered magnesium.oxide that I may produce an oxidate having 25.0% by weight of peroxidesafter 18 hours of oxidation. On oxidizing a portion of the same kerosenewithout the use of magnesium oxide or other basic compound the peroxidecontent increases to about 1.5% to about 5.0%

. rapidly.

after 10,hours and then decreases Thus, it is possible by my process toproduce a hydrocarbonaceous material containing relatively highproportions, i. e. up to 25% or 30% by weight or even higher ofperoxides without employing a concentrating step such as is usuallynecessitated when peroxide concentrates are desired.

The iunctiouv of the basically reacting agent is to react with and thusform salts with the acids which are normally formed along with theperoxides in the oxidation process. These acids may include the lowmolecular weight fatty acids such as formic, acetic, propionic andbutyric acid as well as possibly some of the higher molecular weightcarboxylic acids.

By removing these strong acids the rate of decomposition of theperoxides w hich are formed is decreased for it is It is a furtherobject of my invention to pro- 5 known that strong acids, both mineral.acids and titration.

organic acids. cause the rapid decomposition of peroxides particularlyat the temperatures employed in liquid phase oxidation processes. By

' converting the acids to salts, which salts apparently do not catalyzethe decomposition of peroxides, it is possible to carry on the oxida--tion for-longer periods of time before the rate of decomposition ofperoxides exceeds their rate of formation. Thus, by my process I am ableto produce, by the liquid phase air or oxygen-contaming gas oxidation ofpetroleum fractions,

peroxide-containing oxidates having unusually "tacting employed for insome instances peroxide oxidates have been produced by my process whichhave relatively high peroxide contents and yet have appreciable acidcontents as indicated by In such instances the acidic bodies areapparently high molecular weight weakly acidic compounds which do notinfluence to any great extent the decomposition of peroxides.

While I believe the above theory of the effect of my basically reactingagents is correct I do not wish to be bound by this theory. In selectinga basically reacting agent it is important that the agent does notreduce the rate of formation of peroxides and it i highly desirable thatit does not increase the rate of formation of acids under the conditionof oxidation employed.

Basicallyreacting agents which I have found to be of particular value inmy process include the alkaline earth metals, calcium. magnesium,strontium and barium and the oxides, hydroxides and carbonates of thesemetals: the basically reacting oxides. hydroxides, and carbonates of themetals of the. iron group which metals include iron, cobalt and nickel;thebasically reacting 1 oxides. hydroxides and carbonates of the metalsof the right-hand column of group II of the periodic table which are notclassifiable as alkaline earth metals, which metals include beryllium,zinc, cadmium and mercury;-and the oxides. hydroxides. carbonates andbicarbonates of the alkali metals sodium. potassium and lithium.

In employing these basically reacting agents. I may use them in finelydivided form. such as in the form of a powder, or those which arewater-soluble may be used in the form of a dilute aqueous solution. Theowdered compounds may be made into a slurry or otherwise suspended inthe hydrocarbon fraction being oxidized and the suspension maintained bymeans of mechanical agitation and/or by means of air. or other oxygen-containing gas. agitation during the oxidation process. In a batchoperation sumclent oi the basically reacting agent may be added at thestart of the oxidation .to completely neutralize all of the acids formedduring the processor a portion of the required agent may be added andsumcient additional quantities added during the progress of theoxidation to completely neutralize the acids formed. In a continuousoperation,

I ing agents, an aqueous solution of the agent may 4 tity of basicallyreacting agent with the hydrocarbon feed to the oxidizer.

When employing water-soluble basically reactbe iniected into theoxidation unit with the feed, with the air or oxidizing gas or at anyother convenient point. Thus, a saturated aqueous solution of calciumhydroxide or a solution of calcium hydroxide containing an excess ofcalcium hydroxide may be inlected into the oxidation vessel insuilicient quantities to neutralize the acids formed. Aqueous solutionsofalkali metal carbonates. bicarbonates or hydroxides may be similarlyemployed.

In using the alkaline earth metal themselves it is convenient to usmetal turnings or shavings. supporting them on trays or racks within theoxidation vessel. As a modification of the above processes, metals andother agents described which are not appreciably water-soluble may beemployed in the form of shavings or granules of any convenient size in asecondary vessel outside of the oxidation vessel and the neutralizationof acids eflfected by continuously pumping the hydrocarbon beingoxidized from the oxidation vessel to the secondary vessel where it iscontacted by the basically reacting agent and then returned to theoxidizer.

The amount of basically reacting agent to be employed will usually bebetween about 0.5% and about 5.0% by weight based on the hydrocarbonfeed, however it is a desirable feature that sumcient of the basicmaterial be employed so that unreacted agent is present in the oxidateor is in a secondary vessel, as indicated hereabove, at all-times.

Oxidation stocks which may be employed include substantially allnormally non-gaseous hydrocarbons or normally non-gaseous fractions ofpetroleum which are substantially free from asphaltic bodies and whichcontain less than about 5% to 10% by weight of aromatic hydrocarbons.Thus I may employ light naphthas. gasolines, kerosenes. gas 01]fractions, lubricating oil fractions, 'parafiln wax, residual oils andpetrolatum or micro crystalline petroleum wax. when petroleum fractionsare employed it is preferable that they be first treated with acid orwith a selective solvent to remove the more aromatic and/or highlyoleflnic hydrocarbons and asphaltic bodies. In addition to the variousfractions indicated} may use pure hydrocarbons or relatively narrowboiling hydrocarbon fractions which may be substantially purehydrocarbons. Thus, I may oxidize any naphthene or paraflin ormonoolefin hydrocarbon or narrow boiling fractions comprising thesetypes of hydrocarbons in substantially pure form.

The choice of feed stock will depend upon the character of peroxidesdesired and upon how the peroxides areito be used. Thus, when it isdesired to produce a peroxide-containing fraction which is to be addedto Diesel engine fuel it is desirable to employ as oxidation feed afraction boiling within the boiling range of the Diesel fuel. Thus. aheavy naphtha, a kerosene or a light gas oil fraction is preferablyemployed in this case. If the peroxides are to be used as acceleratorsor initiators in an oxidation process, such as in the oxidation ofparaflln wax it is preferable to employ paramn wax as the feed in theperoxide oxidation process.

In carrying out my partial oxidation process for the production ofsubstantial proportions of it is generally preferable to mix the totalquanhydrocarbon peroxides the hydrocarbon or bydrocarbon fraction .to beoxidized is placed in an oxidation vessel together with a part or all oithe metal or basic compound or agent to be employed and blown with airor other gas containing free oxygen until the desired peroxide con=-tent has been obtained. The oxidation, is preferably eflected attemperatures within the range of about 200 F. to about 275 52, about250F. being a particularly desirable temperature, although I may oxidize attemperatures as low as about 175 F. and as high as about 325 F. Thepressure to be employed will depend upon the stock and upon the otherconditions ct oxidation employed, such as temperature, air-blowing rate,etc.. but may vary from ordinary atmospheric pressure or evenreducedpressures up to any practical pressure limit such as 300 to 500atmospheres pressure. Normally I prefer to operate at ordinaryatmospheric pressure or at pressures up gage. In those instances inwhich only part or the total metal or basic compound required is addedat the start of the oxidation, additional quantities are introduced intothe oxidation vessel as the run progresses. taking care to maintain anexcess of the free metal .or basic compound at all times.

Although the process described above is a batch operation it is withinthe scope 0! my invention to effect the oxidation in a continuous man-.3

ner. Thus, the oxidation stock and the desired quantity or metal orbasic compound may be added continuously to the oxidizer and the oxidatemay be removed from the oxidizer in a continuous manner. Alternatively,the hydrocarbon feed may be introduced continuously into an oxidationchamber containing a relatively large amount of an agent, such asmagnesium in the form of tumings, and further quantities of the agentmay be introduced at intervals during the operation. The amount oroxidate removed from the oxidizer in such operations is so adjusted thatan approximately constant liquid level is maintained within the vessel.

In those instances in which aqueous solutions of the basically reactingagent are employed the aqueous solution may be introduced into theoxidation vessel at such a'rate that an excess of the agent is presentat all times. The partially spent aqueous solution is withdrawn from thebottom of the vessel together with the oxidate and may be separatedtherefrom by settling and decantation.

The oxidation may be efliected in the absence of initiators and/ orcatalysts although I may preter to adc. to the oxidation feed a smallproportion oi an oxidate from a previous operation. The peroxidespresent in the oxidate appear to reduce the induction period and thuseffectively reducethe time required to reach a desirable peroxidecontent in the oxidate.

In preparing an oxidate containing substantial proportions ofhydrocarbon peroxides for use in Diesel fuels, or as oxidationinitiators, accelerators, or the like, the oxidate obtained in the abovedescribed manner may be washed with a dilute aqueous alkali, such asabout a 2% to about a NaOH solution, or about a 5% to about solution 0!sodium or potassium carbonate to remove any acidic bodies contained inthe oxidate and then washed with water and finally dried by ,settling orother means. In this manner, a product containing about 5% to about byweight of peroxides in a hydrocarbon menstruum is obto .about 100 pounds.per square inch 0 treated iuel.

tained which is substantially free from organic acidity.

In preparing a high quality Diesel engine fuel I may blend a Dieseltuelof substantially any quality with about 1% my peroxide oxidate. Byadding the peroxide oxidate to Diesel fuel it is possible to increasethe cetane number of the fuel up to about fifteen to twenty points abovethe cetane value of the un- Cetane number relates to the intervalbetween the instant of fuel injection and the instant of ignition oithe'iuel in the combustion chamber of an engine and is described in the1943 issue of the A. S. T. M. Standards on Petroleum Products andLubricants prepared by A. S. T. M. Committee D-2 on Petroleum Productsand Lubricants, page 172. Thus, a 45 octane num.- ber Diesel fuel may beincreased to a 60 octane number iuel by the addition oi 16.0% by weightof a kerosene peroxide oxldate containing 20%- by weight of peroxides.

The rollowing specific examples will serve to further illustrate myinvention:

Example I To 1700 grams of kerosene having a distillation range of 344F. to 571 F., a gravity of 435 A. P. I. and comprising substantiallyequal proportions of naphthene and paraflln hydrocarbons was added 3.4grams of powdered magnesium oxide and the mixture placed in an oxidationves so] where it was blown with air at the rate of 2.5 cubic feet perminute per barrel of charge at a temperature of 250 F. under normalatmospheric pressure. Additional 1.7-gram increments of magnesium oxidewere added every two hours and the run was continued for a total of 29hours. A total 0127.2 grams or 1.6% by weight of magnesium oxide wasemployed. The peroxide content ot the oxidate as determined at variousintervals during the run was: I

. Per Cent The peroxide content was determined by titration withtitanium chloride according to the method described by Morrell et 9.1.,Industrial Engineering Chemistry, vol. 26, page 655 (1934).

In order to show the effect of the absence of the basically reactingagent, a 2000 gram portion of kerosene oi the same character as thatused above was air blown at atmospheric pressure and at 250 F. for aperiod of 15 hours. Test data on samples withdrawn at various intervalsduring the progress of the run were as follows:

Per Cent Weight 4 o Peroxidcs to about by weight oi,

Peroxides 1.- Z'xample II To 1900 grams oi kerosene o the characteremployed above was added 19 grams of magnesium oxide. The oxidation waseiiected under the conditions or temperature, pressure and air blowingrate employed in Example I and after six hours an additional 1% byweight of magnesium a blowingwithairatarateotflcubicieetller oxide testsand acid number determinations on samples or the oxidate withdrawn fromthe oxidizer at various intervals oxide was added. The oxidation wascontinued v oxidation 'mafloum: for a total or 22 hours and during thistime a tom tal of 57 grams or 3% by weight of magnesium cm oxide hadbeen employed. Samples removed for b -ggg. analysis as the runprogressed were analysed ior 5? m peroxide content with the followingresults: Peroxides x0 g V 8 L cm 10 111: t Hours w ht 11 no u. I 14 12.017. Peroxides 18 as so. a s o 20 g 22 Example V 7 1s aa'o To 1900 gramsoi kerosene was added 19 Q 26 rams or 1% by weight of calcium carbonateand this mixture was air blown at 250 1". under nor- A 1,000 gramportion of the oxidate containing 20.1 by weight of the peroxides waswashed with two 100 ml. portions of aqueous potassium carbonate solutioncontaining 15% by weight of K200: and then washed with water to removeany potassium carbonate remaining in the oxidate. The washed product wasallowed to settle until clear and there was recovered 950 grams of aperoxide oxidate containing 18.0% by weight of peroxides. A 120 grainportion of this washed oxidate was added to and thoroughly mixed with1,000 grams or a Diesel fuel having a cetane number of 47.5 and theresulting blend had a cetane number of 58.0.

Example In To 60,000 grams oi kerosene was added 1,200 grams or 2% byweight or magnesium oxide and this mixture was air blown using an airrate of 2.5 cubic feet per minute per barrel of charge at 250 F. to 275F. at a pressure oi 95 pounds per square inch gage. The oxidation wascontinued for a total of thirteen hours without further additions ofmagnesium oxide. The results of peroxide tests on samples withdrawn atvarious intervals during the oxidation were as follows:

Per Cent Hours We ht Perorldes The final product containing 20.9% byweight of peroxides had an acid number of 9.5 mg. KOH/g.

Example IV A 1700 gram portion of kerosene was oxidized in the presenceor 51 grams of 3% by weight or magnesium turnings. The oxidation waselected at 250 F. under normal atmospheric pressure by Per Cent Hours Wet I Perci r les s z s: a:

' Example Vi To 2000 grams or paramn wax having a melting point or 1".to F. was added 60 grams or 3.0% by weight or magnesium oxide and themixture was air blown at 250 1". for a period of 25 hours at normalatmospheric pressure using an air rate of 2.5;ciibic feet per minute perbarrel oi charge. Samples of the wax were withdrawn from the oxidizeratvarious intervals during the oxidation and analyzed for peroxide andacid content with the following results:

In order to show the eilect oi the absence of the basically reactingagent a 2000 gram portlon oi the same paramn wax was oxidized under thesame conditions or temperature. pressure, time and blowing rate but inthis case no agent was used. The results of tests on samples removed atintervals during the 25 hour period of oxidation were as follows;

Per Cent 7 Weight oi Peroxides Hours about 300 F. at pressures sumcientto maintain said liquid phase in the presence oi an amount of from 0.5to 5.0% by weight of a basically reacting compound of an alkaline earthmetal maintaining at all times the presence of the basically reactingagent to an acid number not exceeding about 21 mg. KOH/g. to produce anoxidate containing between about and about 30% oi said paraffinhydrocarbon peroxide and separating the partially spent basicallyreacting agent from the oxidate.

2. A process for the production of a paraflln hydrocarbon peroxideconcentrate containing between about 5% and about 30% by weight ofparaffin hydrocarbon peroxides which comprises air blowing normallynon-gaseous paraflin hydrocarbon iraction in the liquid phase attemperatures between about 225 1". and about 300 'F.

and at pressures suiiicient to maintain said liquid phase in thepresence of an amount or from 0.5 to 5.0% by weight of a basicallyreacting com- 5 pound of an alkaline earth metal maintaining at 0 Numberall times the presence of the basically reacting agent to an acid numbernot exceeding about 21 mg. KOH/g. and subsequently separating theresulting oxidate from the partially spent basically reacting agent.

3. A process as in claim 2 in which said basically reacting agent is analkaline earth metal oxide.

4. A process as in claim 2 in which said basically reacting agent is acarbonate.

5. A process as in claim 2 in which said basically reacting agent ismagnesium oxide.

6. A process as in claim 2 in which said basically reacting agent iscalcium carbonate.

7. A process as in claim 2 wherein said normally non-gaseous parafllnhydrocarbon fraction is a petroleum fraction having a distillation rangeof irom about 344 F. to about 571 F.

8. A process as in claim 2 wherein said normally non-gaseous parafllnhydrocarbon fraction is paraflln wax.

PHILIP D. BREWER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Hartmann Aug. 29, 1933 Friedolsheim Nov.20, 1934 Penniman Mar. 26, 1935 FOREIGN PATENTS Country Date GermanyJan. 2, 1922 Great Britain Mar. 31, 1922 Number

